package org.foreningsgatan.modular.common.primitive;

/*
 * Copyright (c) 2009 Joakim Back
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/**
 * Attack, Hold, Release Envelope.
 * See http://en.wikipedia.org/wiki/ADSR_envelope for description.
 * 
 * @author Joakim Back
 *
 */
public class AHREnvelope {
	private double attack;
	private double hold;
	private double release;
	private double length;
	
	public AHREnvelope(double attack, double hold, double release) {
		this.attack = attack;
		this.hold = hold;
		this.release = release;
		this.length = attack + hold + release;
	}
	
	/**
	 * Determine if position is within envelope span
	 * @param position
	 * @return
	 */
	public boolean within(double position) {
		return PrimitiveUtils.within(position, 0, length);
	}
	
	/**
	 * Retrieve envelope value at position
	 * @param position
	 * @return
	 */
	public double get(double position) {
		if (!within(position)) {
			return 0.0;
		}
		
		if (position < attack) {
			return position / attack;
		}
		
		position -= attack;
		
		if (position < hold) {
			return 1.0;
		}
		
		position -= hold;
		
		return 1.0 - (position / release);
	}
}
